Generally strip roofing shingles, be they tabbed or undivided shingle sheets or tabbed composite shingles having a narrow sheet laminated beneath the tabbed portion, are supplied in two sizes, namely English and Metric sheet size. The English strip shingle measures 12 inches high by 36 inches long and has a 5 inch exposure between applied courses. Eighty shingle pieces of this dimension are required to cover 100 square feet of roof deck. The Metric sheet measures 13.25 inches high by 39.375 inches long and has a 5.625 inch exposure between applied courses, requiring 65 shingles to cover the same surface area of roof deck.
When reroofing, problems occur due to incompatibility between the Metric and English dimensions. The most common problem arises in the use of the Metric shingle which is less expensively installed for reroof over shingles of English dimension. During application, the roofer has no point of reference to insure horizontal alignment of the reroofing shingle courses and must either rely on his judgement or provide reference lines by measuring and striking chalk lines at intervals up the original roof courses. Also, because of the lack of registry between the English and Metric sizes and the shape conformance of current standard fiber glass based asphalt products, roofing Metric over English shingles, or visa versa, results in objectionable distortions on the surface of the finished roof which imparts unsightly irregularity. Further, the nature of the distortions can affect the ultimate weather-proofing and life of the completed roof assembly. Additionally, nailing of Metric over English or vice versa leads to problems of breakage and tearing where the nailing of the overlay shingles recurrently align and penetrate in a cantilevered area of the underlay formed by the overlapping of underlay courses. To minimize the above problems, it has been necessary for the manufacturer to maintain separate inventories of English and Metric shingles for reroofing purposes.
Difficulties also arise when reroofing with Metric over Metric or English over English since the manufactured batches of shingles are subject to some irregularity in height. A slight difference, e.g. 1/16 inch, which may occur between the original and the reroofing shingle, becomes significant after many courses of reroofing material have been laid since such alignment problems are cumulative in the overall installation. Additionally, the many courses which must be laid with conventional overlapping and nailing, considerably increases the weight of the roofing and presents many areas for failure around the nails which penetrate the roof deck, conventionally at a distance of 10 inches apart along a horizontal line for each course. Such alignment of courses, and overlapping and nailing of each course requires considerable time and precision for proper installation. In certain instances the roof deck is not sufficiently reinforced to take additional weight over 1 or 2 roofing assemblies. In such cases, at least one underlay roofing must be removed before reroofing. Accordingly, there has been a long felt need for reroofing shingles which eliminate difficulties in alignment, provide adequate weatherproofed coverage, decrease occasions for tearing at nail sites and which minimize weight load, areas of deformation and time consuming installation operations.
It is an object of this invention to eliminate certain of the above problems and to minimize others.
Another object is to provide a reroofing shingle of specific dimension common to courses of English and Metric size shingles which obviates errors in alignment, provides adequate weatherproofed coverage, minimizes area of deformation, provides a lighter reroof covering and greatly reduces time and expense of installation.